Circuit board and circuit module

ABSTRACT

A circuit board and a circuit module more accurately provide impedance matching between an antenna coil and an electronic component electrically connected to the antenna coil, and include a board body including board portions and a plurality of laminated insulating material layers made of a flexible material. An antenna coil includes coil conductors provided in the board portion. Wiring conductors are provided in the board portion and electrically connected to the antenna coil. The board portion has a structure that is less likely to deform than the board portion. An integrated circuit electrically connected to the wiring conductors is mounted on the board portion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a circuit board and a circuit module,and more specifically, relates to a circuit board and a circuit moduleeach including an antenna coil.

2. Description of the Related Art

As an existing circuit board, for example, the flexible sheet describedin International Publication No. 2007/015353 is known. Hereinafter, theflexible sheet will be described with reference to the drawing. FIG. 7is a configuration diagram of the flexible sheet 500 described inInternational Publication No. 2007/015353.

As shown in FIG. 7, the flexible sheet 500 is one sheet formed from aflexible material, and is composed of coil pattern portions 500 a to 500d and a mounting portion 501. Coil conductors 502 a to 502 d areprovided on the pattern portions 500 a to 500 d, respectively. The coilconductors 502 a to 502 d constitute an antenna coil.

Further, a hard circuit board 600 is mounted on the mounting portion501. Moreover, a semiconductor element 602 that performs a communicationfunction for transmitting and receiving signals via the antenna coil toand from an external device is mounted on the circuit board 600. Theflexible sheet 500 described above is mounted in an electronic device orthe like in a state of being bent at dotted lines L1 to L4 (the dottedline L3 is indicated as a solid line since it overlaps the circuit board600) in FIG. 7 and folded in a compact form. The flexible sheet 500performs non-contact communication with an external device via theantenna coil to exchange signals.

Meanwhile, as described below, the flexible sheet 500 has a problem inthat it is difficult to provide impedance matching between thesemiconductor element 602 and the antenna coil, which is composed of thecoil conductors 502 a to 502 d. Specifically, in the flexible sheet 500,the antenna coil is formed on the flexible sheet 500. The semiconductorelement 602 is mounted on the circuit board 600 mounted on the flexiblesheet 500. Thus, between the antenna coil and the circuit board 600,there are two connection portions, namely, a connection portion betweenthe flexible sheet 500 and the circuit board 600 and a connectionportion between the circuit board 600 and the semiconductor element 602.At the connection portions, a wiring width changes, and hence impedancematching is likely to deteriorate. Thus, in the flexible sheet 500, inorder to provide impedance matching between the antenna coil and thesemiconductor element 602, it is desired to reduce the number of theconnection portions.

SUMMARY OF THE INVENTION

Therefore, preferred embodiments of the present invention provide acircuit board and a circuit module that can more accurately provideimpedance matching between an antenna coil and an electronic componentelectrically connected to the antenna coil.

A circuit board according to a preferred embodiment of the presentinvention includes a board body including a first board portion and asecond board portion and also including a plurality of laminatedinsulating material layers made of a flexible material; an antenna coilincluding coil conductors provided on the insulating material layers inthe first board portion; and wiring conductors provided on theinsulating material layers in the second board portion and electricallyconnected to the antenna coil. The second board portion has a structurethat is less likely to deform than the first board portion. Anelectronic component is mounted on the second board portion so as to beelectrically connected to the wiring conductors.

A circuit module according to another preferred embodiment of thepresent invention includes a board body including a first board portionand a second board portion and also including a plurality of laminatedinsulating material layers made of a flexible material; an antenna coilincluding coil conductors provided on the insulating material layers inthe first board portion; wiring conductors provided on the insulatingmaterial layers in the second board portion and electrically connectedto the antenna coil; and an electronic component mounted on the secondboard portion in a state of being electrically connected to the wiringconductors. The second board portion has a structure that is less likelyto deform than the first board portion.

According to various preferred embodiments of the present invention,impedance matching can more accurately be provided between an antennacoil and an electronic component electrically connected to the antennacoil.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are external perspective views of a circuit boardaccording to a preferred embodiment of the present invention.

FIG. 2 is an external perspective view of a circuit module that includesthe circuit board in FIGS. 1A and 1B.

FIG. 3 is an exploded perspective view of the circuit board in FIGS. 1Aand 1B.

FIG. 4 is a diagram illustrating a state where the circuit module inFIG. 2 is mounted in an electronic device.

FIG. 5 is a diagram illustrating a state where a circuit moduleaccording to a modified example is mounted in an electronic device.

FIGS. 6A and 6B are external perspective views of a circuit boardaccording to a modified example.

FIG. 7 is a configuration diagram of the flexible sheet described inInternational Publication No. 2007/015353.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a circuit board and a circuit module according to preferredembodiments of the present invention will be described with reference tothe drawings.

Hereinafter, a circuit board and a circuit module according to variouspreferred embodiments of the present invention will be described withreference to the drawings. FIGS. 1A and 1B are external perspectiveviews of a circuit board 10 according to a preferred embodiment of thepresent invention. FIG. 2 is an external perspective view of a circuitmodule 100 that includes the circuit board 10 in FIGS. 1A and 1B. FIG. 3is an exploded perspective view of the circuit board 10 in FIGS. 1A and1B. FIG. 4 is a diagram illustrating the circuit module 100 in FIG. 2 ismounted in an electronic device. Hereinafter, a direction in whichinsulating material layers are laminated when producing the circuitboard 10 is defined as a lamination direction. The lamination directionis defined as a z-axis direction, and a longitudinal direction of thecircuit board 10 is defined as an x-axis direction. In addition, adirection perpendicular to the x-axis direction and the z-axis directionis defined as a y-axis direction.

As shown in FIGS. 1A and 1B, the circuit board 10 includes a board body11. The board body 11 includes board portions 12 (12 a to 12 c). Theboard portion 12 a preferably has a rectangular or substantiallyrectangular shape and includes an antenna coil L. In addition, amagnetic material layer 14 is provided on a principal surface (backsurface) of the board portion 12 a on a negative direction side in thez-axis direction.

The board portion 12 b preferably has a rectangular or substantiallyrectangular shape, and has, in a principal surface (front surface)thereof on a positive direction side in the z-axis direction, a mountingsurface on which an integrated circuit (electronic component) 102 andchip elements (electronic components) 104 and 106 are mounted as shownin FIG. 2. The board portion 12 a and the board portion 12 b togetherdefine a rectangle having long sides in the x-axis direction. In FIGS.1A and 1B and 2, the boundary between the board portions 12 a and 12 bis indicated by a dotted line.

The board portion 12 c preferably has a rectangular or substantiallyrectangular shape smaller than those of the board portions 12 a and 12b, and includes, in a principal surface (front surface) thereof on thepositive direction side in the z-axis direction, a mounting surface onwhich a connector (electronic component) 108 is mounted as shown in FIG.2. The board portion 12 c is provided on a positive direction side inthe x-axis direction with respect to the board portion 12 b.

As shown in FIG. 3, the board body 11 preferably includes a plurality(for example, three in FIG. 3) of laminated insulating material layers30 (30 a to 30 c) made of a flexible material (e.g., a thermoplasticresin such as a liquid crystal polymer). Hereinafter, a principalsurface of the insulating material layer 30 on the positive directionside in the z-axis direction is referred to as a front surface, and aprincipal surface of the insulating material layer 30 on the negativedirection side in the z-axis direction is referred to as a back surface.

First, the board portion 12 a will be described. As shown in FIG. 3, theboard portion 12 a preferably includes laminated board portion layers 50(50 a to 50 c) of the insulating material layers 30 (30 a to 30 c). Inaddition, as shown in FIGS. 1A to 3, the antenna coil L and the magneticmaterial layer 14 are provided in the board portion 12 a.

The antenna coil L radiates high-frequency signals as radio waves to theoutside of the circuit board 10 and receives radio waves from theoutside of the circuit board 10. As shown in FIG. 3, the antenna coil Lpreferably has a spiral shape and preferably includes coil conductors 36b and 36 c and a via-hole conductor b4.

The coil conductor 36 b has a spiral shape extending toward the centerwhile turning clockwise, when being seen in a planar view from thepositive direction side in the z-axis direction. The coil conductor 36 bis provided on the front surface of the board portion layer 50 b. Thecoil conductor 36 c has a spiral shape extending toward the center whileturning counterclockwise, when being seen in a planar view from thepositive direction in the z-axis direction. The coil conductor 36 c isprovided on the front surface of the board portion layer 50 c. Thevia-hole conductor b4 is arranged to extend through the board portionlayer 50 b in the z-axis direction and connects an end of the coilconductor 36 c that is close to the center, to an end of the coilconductor 36 c that is close to the center.

The magnetic material layer 14 is preferably made of a resin containingmagnetic material powder, and is arranged on the back surface of theboard portion 12 a so as to cover substantially the entirety thereof.The magnetic material layer 14 prevents leakage of a magnetic fluxgenerated by the antenna coil L, to the negative direction side in thez-axis direction with respect to the circuit board 10. Preferably, themagnetic material layer 14 has flexibility but is less likely to deformthan a sheet made of the flexible material used for the insulatingmaterial layers 30 of the board portion 12 a, in order to make the boardportion 12 a less likely to deform due to the magnetic material layer14. Preferably, the magnetic material layer 14 is thicker than theinsulating material layers 30.

Next, the board portion 12 b will be described. The board portion 12 bpreferably includes laminated board portion layers 52 (52 a to 52 c) ofthe insulating material layers 30 (30 a to 30 c). In addition, as shownin FIGS. 1A to 3, a resist film (omitted in FIG. 3), external electrodes18, 20, and 22, wiring conductors 32 (32 a to 32 c), a ground conductor40, and via-hole conductors b1, b3, and b5 to b9 are provided in theboard portion 12 b.

The external electrodes 18 are electrodes on which the integratedcircuit 102 in FIG. 2 is mounted via solder or the like, and include aplurality of electrodes provided on the front surface of the boardportion layer 52 a so as to be arranged to define a rectangular shape asshown in FIG. 3. The external electrodes 20 and 22 are electrodes onwhich the chip elements 104 and 106 in FIG. 2 are mounted, respectively,and each include two electrodes provided on the front surface of theboard portion layer 52 a so as to be spaced apart from each other at apredetermined interval.

The wiring conductors 32 a to 32 c are line conductors provided on thefront surfaces of the board portion layers 52 a to 52 c, respectively.In addition, the wiring conductors 32 a are connected to any of theexternal electrodes 18, 20, and 22. The via-hole conductors b1 extendthrough the board portion layer 52 a in the z-axis direction and connectthe wiring conductors 32 a to the wiring conductors 32 b. The via-holeconductors b6 extend through the board portion layer 52 b in the z-axisdirection and connect the wiring conductors 32 b to the wiring conductor32 c.

Further, the via-hole conductor b3 extends through the board portionlayer 52 a in the z-axis direction and connects the wiring conductor 32a to the coil conductor 36 b. The via-hole conductors b5 and b7 extendthrough the board portion layers 52 b and 52 c, respectively, in thez-axis direction and are connected to each other to connect the wiringconductor 32 a to the coil conductor 36 c. As described above, theantenna coil L is electrically connected to the integrated circuit 102and the chip elements 104 and 106 via the wiring conductors 32 a to 32 cand the via-hole conductors b1 and b3 to b7 as shown in FIG. 3.

The ground conductor 40 is arranged so as to cover substantially theentirety of the front surface of the board portion layer 52 b, and aground potential is applied thereto. The ground conductor 40 preferablyis produced from a harder material than the insulating material layers30 and hence is less likely to be bent than the insulating materiallayers 30. Thus, the board portion 12 b has a structure that is lesslikely to deform than the board portion 12 a, since the ground conductor40 is provided therein. Moreover, in order to prevent the groundconductor 40 from being short-circuited to the wiring conductors 32 b,the ground conductor 40 is not provided around the wiring conductors 32b. The ground conductor 40 described above is connected to the wiringconductor 32 a via the via-hole conductor b8 extending through the boardportion layer 52 a in the z-axis direction.

The via-hole conductors b9 extend through the board portion layer 52 ain the z-axis direction and connect the wiring conductors 32 a to wiringconductors 34 b (described in detail below).

Next, the board portion 12 c will be described. The board portion 12 cpreferably includes laminated board portion layers 54 (54 a to 54 c) ofthe insulating material layers 30 (30 a to 30 c). In addition, as shownin FIGS. 1A to 3, external electrodes 24, the wiring conductors 34 b, aground conductor 42, and via-hole conductors b2 and b10 are provided inthe board portion 12 c.

The external electrodes 24 are electrodes on which the connector 108 inFIG. 2 is mounted via solder, and include four electrodes arranged onthe front surface of the board portion layer 52 a so as to be aligned inthe y-axis direction as shown in FIG. 3.

The wiring conductors 34 b are line conductors provided on the frontsurface of the board portion layer 54 b, and extending in the x-axisdirection. Each wiring conductor 34 b is connected to the wiringconductor 32 b or the via-hole conductor b9.

The via-hole conductors b2 extend through the board portion layer 54 ain the z-axis direction and connect the external electrodes 24 to thewiring conductors 34 b. Thus, the connector 108 is electricallyconnected to the integrated circuit 102 via the wiring conductors 32 a,32 b, and 34 b and the via-hole conductors b2 and b9.

The ground conductor 42 is arranged so as to cover a portion of thefront surface of the board portion layer 54 c, and the ground potentialis applied thereto. Specifically, the ground conductor 42 preferablyincludes a region in which the connector 108 in FIG. 2 is provided, whenbeing seen in a planar view from the z-axis direction. The groundconductor 42 is not provided in a region in which the wiring conductors34 b are provided, when being seen in a planar view from the z-axisdirection. The ground conductor 42 preferably is produced from a hardermaterial than the insulating material layers 30 and hence is less likelyto be bent than the insulating material layers 30. Thus, a portion ofthe board portion 12 c has a structure that is less likely to deformthan the board portion 12 a, since the ground conductor 42 is providedtherein. The ground conductor 42 described above is connected to thewiring conductor 34 b via the via-hole conductor b10 extending throughthe board portion layer 54 b in the z-axis direction.

In the circuit board 10, as shown in FIG. 2, the integrated circuit 102and the chip elements 104 and 106 are mounted on the external electrodes18, 20, and 22, respectively, on the front surface of the board portion12 b. Thus, the integrated circuit 102 and the chip elements 104 and 106are electrically connected to the wiring conductors 32 a to 32 c. Inaddition, the connector 108 is mounted on the external electrodes 24 onthe front surface of the board portion 12 c. Thus, the connector 108 iselectrically connected to the wiring conductors 34 b. As describedabove, the circuit board 10, the integrated circuit 102, the chipelements 104 and 106, and the connector 108 constitute the circuitmodule 100. The integrated circuit 102 is, for example, a circuit thatprocesses transmission and reception signals of the antenna coil L. Inaddition, each of the chip elements 104 and 106 is, for example, acapacitor, a coil, or a noise filter including them.

The circuit module 100 constructed as described above is preferably bentin a U shape and used as shown in FIG. 4. Specifically, the circuitmodule 100 is bent in a U shape at the boundary between the boardportions 12 a and 12 b such that the front surface of the board body 11defines an outer peripheral surface and the back surface of the boardbody 11 defines an inner peripheral surface. Thus, the magnetic materiallayer 14 is located between the board portions 12 a and 12 b.

It should be noted that when seen in a planar view from the z-axisdirection, the boundary between the boards 12 a and 12 b in the circuitboard 10 is a straight line passing through a third region sandwichedbetween a first region in which the antenna coil L has a spiral shapeand a second region in which the ground conductor 40 is provided. In thepresent preferred embodiment, when being seen in a planar view from thez-axis direction, the boundary between the boards 12 a and 12 b is astraight line located midway between a side, on a negative directionside in the x-axis direction, of the region in which the antenna coil Lhas a spiral shape and a side of the ground conductor 40 on the positivedirection side in the x-axis direction.

Hereinafter, a method for manufacturing the circuit board 10 will bedescribed with reference to the drawings. Hereinafter, the case whereone circuit board 10 is produced will be described as an example.However, in reality, a plurality of circuit boards 10 may preferably besimultaneously produced by laminating and cutting large insulatingmaterial layers 30 (flexible sheets).

First, insulating material layers 30 having copper foil formed on theentireties of the front surfaces thereof are prepared. Next, a laserbeam is applied from the back surface side to locations (see FIG. 3) inthe insulating material layers 30 a and 30 b where the via-holeconductors b1 to b10 are to be formed, to form via holes.

Next, the external electrodes 18, 20, 22, and 24 and the wiringconductors 32 a shown in FIG. 3 are formed on the front surface of theinsulating material layer 30 a by a photolithographic process.Specifically, resists having the same shapes as those of the externalelectrodes 18, 20, 22, and 24 and the wiring conductors 32 a shown inFIG. 3 are printed on the copper foil of the insulating material layer30 a. Then, etching treatment is performed on the copper foil to removethe portion of the copper foil that is not covered with the resists.Then, the resists are removed. By so doing, the external electrodes 18,20, 22, and 24 and the wiring conductors 32 a are formed on the frontsurface of the insulating material layer 30 a as shown in FIG. 3.Further, a resin is applied to the front surface of the insulatingmaterial layer 30 a to form the resist film 16 shown in FIGS. 1A and 1B.

Next, the wiring conductors 32 b and 34 b, the coil conductor 36 b, andthe ground conductor 40 shown in FIG. 3 are formed on the front surfaceof the insulating material layer 30 b by a photolithographic process,for example. Further, the wiring conductor 32 c, the coil conductor 36c, and the ground conductor shown in FIG. 3 are formed on the frontsurface of the insulating material layer 30 c by a photolithographicprocess, for example. These photolithographic processes are preferablythe same as the photolithographic process performed when forming theexternal electrodes 18, 20, 22, and 24 and the wiring conductors 32 a,and thus the description thereof is omitted.

Next, the via holes formed in the insulating material layers 30 a and 30b are filled with a conductive paste containing copper as a principalcomponent, to form the via-hole conductors b1 to b10 shown in FIG. 3.

Next, the insulating material layers 30 a to 30 c are stacked in order.Then, forces are applied to the insulating material layers 30 a to 30 cfrom upper and lower directions in the lamination direction, topressure-bond the insulating material layers 30 a to 30 c. By so doing,the circuit board 10 shown in FIGS. 1A and 1B is obtained.

According to the circuit board 10 and the circuit module 100 describedabove, impedance matching can more accurately be achieved between theantenna coil L and the integrated circuit 102. Specifically, in theexisting flexible sheet 500 shown in FIG. 7, the antenna coil is formedon the flexible sheet 500. The semiconductor element 602 is mounted onthe circuit board 600 mounted on the flexible sheet 500. Thus, betweenthe antenna coil and the circuit board 600, there are two connectionportions, namely, the connection portion between the flexible sheet 500and the circuit board 600 and the connection portion between the circuitboard 600 and the semiconductor element 602. At the connection portions,a wiring width changes, and hence impedance matching is likely todeteriorate. Thus, in the flexible sheet 500, between the antenna coiland the semiconductor element 602, impedance matching may greatlydeteriorate at the two portions.

For that reason, in the circuit board 10, the integrated circuit 102 isallowed to be mounted directly on the circuit board 10 without using aboard that is as hard as the circuit board 600. Specifically, in thecircuit board 10, the ground conductor 40 is provided in the boardportion 12 b on which the integrated circuit 102 is mounted. Due tothis, the board portion 12 b has a structure that is less likely todeform than the board portion 12 a. Thus, in the circuit board 10, theintegrated circuit 102 is allowed to be mounted directly on the boardportion 12 b. Due to this, between the antenna coil L and the integratedcircuit, there is only one connection portion. Therefore, in the circuitboard 10, it is possible to more accurately provide impedance matchingbetween the antenna coil L and the integrated circuit 102 than in theflexible sheet 500.

Further, in the circuit board 10, the board body 11 preferably includesthe laminated insulating material layers 30 made of a flexible material.Thus, it is possible to relatively easily bend the region other than theregions in which the ground conductors 40 and 42 are provided.Therefore, similarly to the flexible sheet 500, the board body 11 isallowed to be bent and folded in a compact form.

Further, the characteristics of the antenna coil L do not greatly changeeven when the board portion 12 a is slightly bent. Thus, the circuitboard 10 has a structure in which it is easy to bend the board portion12 a, whereby the circuit board 10 is allowed to easily be mounted to ahousing of an electronic device.

Further, in the circuit board 10, the insulating material layers 30 arepreferably produced from a liquid crystal polymer. The liquid crystalpolymer has lower hygroscopicity than ceramic materials such as epoxyglass. Thus, the circuit board 10 can prevent deformation caused bymoisture absorption as compared to a circuit board produced from aceramic material such as epoxy glass. As a result, the circuit board 10can prevent changes in characteristics of the antenna coil L caused bydeformation of the board body 11.

Further, in the circuit board 10, as described below, since the magneticmaterial layer 14 is provided, shifting of the resonant frequency of theantenna coil L can be prevented. Specifically, if the magnetic materiallayer 14 is not provided, when the board body 11 is bent as shown inFIG. 4, a magnetic flux generated by the antenna coil L in the boardportion 12 a reaches the board portion 12 b. Thus, when the magneticflux passes through the wiring conductors 32 a to 32 c in the boardportion 12 b, an eddy current occurs at the wiring conductors 23 a to 32c. When the eddy current occurs, a magnetic flux occurs in a directionin which the magnetic flux generated by the antenna coil L is disturbed.Thus, the inductance value of the antenna coil L decreases. As a result,the resonant frequency of the antenna coil L shifts.

Thus, in the circuit board 10, as shown in FIG. 4, when the board body11 is bent, the magnetic material layer 14 is located between the boardportions 12 a and 12 b. Due to this, the magnetic flux generated by theantenna coil L is confined in the magnetic material layer 14, and themagnetic flux is prevented from reaching to the board portion 12 b. As aresult, a decrease of the inductance value of the antenna coil L isprevented, and a shift of the resonant frequency of the antenna coil Lis prevented.

Hereinafter, a circuit board and a circuit module according to modifiedexamples of preferred embodiments will be described with reference tothe drawings. FIG. 5 is a diagram illustrating a state where a circuitmodule 100′ according to a modified example is mounted in an electronicdevice.

As shown in FIG. 4, the circuit module 100 is bent at the boundarybetween the board portions 12 a and 12 b once and used. Meanwhile, asshown in FIG. 5, the circuit module 100′ is bent at the boundary betweenthe board portions 12 a and 12 b and at the boundary between the boardportions 12 b and 12 c twice and used, and is formed in an S shape. Dueto this, the circuit module 100′ becomes compact in an xy plane ascompared to the circuit module 100.

In the circuit module 100′, the magnetic material layer 14 is providedon the front surface of the board portion 12 a in order to locate themagnetic material layer 14 between the board portions 12 a and 12 b. Theother structure of the circuit module 100′ is the same as that of thecircuit module 100, and thus the description thereof is omitted.

Next, a circuit board 10′ according to a second modified example ofpreferred embodiments of the present invention will be described withreference to the drawing. FIGS. 6A and 6B are external perspective viewsof the circuit board 10′ according to the second modified example.

A magnetic material layer 14′ shown in FIGS. 6A and 6B has a larger areathan that of the board portion 12 a so as to cover the boundary betweenthe board portions 12 a and 12 b. The magnetic material layer 14′ is asheet-shaped member obtained by dispersing magnetic material powder suchas ferrite in a resin, and can also serve as a reinforcing member toreinforce the board portion 12 a and the boundary between the boardportions 12 a and 12 b, the board portion 12 a having a flexibility.Thus, since the magnetic material layer 14′ is arranged so as to coverthe boundary between the board portions 12 a and 12 b to which stress isrepeatedly applied due to bending or the like, breakage at the boundarybetween the board portions 12 a and 12 b is prevented. In addition,since the magnetic material layer 14′ has a larger area than that of theboard portion 12 a so as to cover the boundary between the boardportions 12 a and 12 b, for example, even when the circuit board 10′ isbent similarly as in FIG. 4, a magnetic flux generated by the antennacoil L is assuredly confined in the magnetic material layer 14′. As aresult, reach of the magnetic flux generated by the antenna coil L, tothe board portion 12 b is further prevented, and thus thecharacteristics of the antenna coil L are even more significantlyimproved.

Preferred embodiments of the present invention are applicable to circuitboards and circuit modules, in particular, useful for signal lines and amethod for manufacturing the same, and in particular, excellent in beingable to more accurately provide impedance matching between an antennacoil and an electronic component electrically connected to the antennacoil.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

1. (canceled)
 2. A circuit board, comprising: a first board portion anda second board portion each including insulating layers made of aflexible material; an antenna coil including coil conductors provided onthe insulating layers in the first board portion; wiring conductorsprovided on the insulating layers in the second board portion andelectrically connected to the antenna coil; and a magnetic substancelayer; wherein the first board portion and the second board portion arearranged so as to include regions that face each other; and the magneticsubstance layer is provided with the first board portion and is locatedbetween the coil conductors of the first board portion and the wiringconductors of the second board portion.
 3. The circuit board accordingto claim 2, wherein a board body, which includes the first board portionand the second board portion, is bent such that the first board portionand the second board portion include the regions facing each other. 4.The circuit board according to claim 2, wherein the magnetic substancelayer has an area size that is larger than that of the first boardportion in plan view.
 5. The circuit board according to claim 2, whereinelectronic components electrically connected to the wiring conductorsare mounted on a principal surface of the second body portion, which isopposite to the region of the second body portion that faces the regionof the first body portion.